# Copyright (c) 2021 Intel Corporation.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


def checksum(binary):
    """Calculate checksum"""
    prev, total = "", 0
    for i in range(len(binary)):
        k = i * 16
        if k >= len(binary):
            break
        if not prev:
            prev = binary[k : k + 16]
            continue
        now = binary[k : k + 16]
        total = int(prev, 2) + int(now, 2)
        if total >> 16:
            total = (total >> 16) + (total & 0xFFFF)
        prev = bin(total)
    return total ^ 0xFFFF
